This invention relates to a comminutor-pump assembly of a type suitable for use in a system for the application of livestock waste to land by irrigation. These systems are becoming increasingly popular because of the low cost and the ease of use thereof as compared with other systems. However, irrigation systems of this type require reliable means for reducing the size of the solids so as to avoid clogging of the centrifugal pump and the openings in the sprinkler heads or large guns used to spray the sewage and other solids out onto the field. It is also essential to maintain sufficient pumping pressure in the system.
A comminutor-pump assembly of the indicated type is shown in U.S. application Ser. No. 389,676 and has many features and advantages. For example, the comminutor-pump assembly of said application is constructed so that the comminutor and pump are driven by the same prime mover with the pump being arranged to draw the sewage into a comminution chamber containing a rotating hollow comminutor cylinder which functions as a combination cutter and strainer. The solids in the sewage are comminuted to a size small enough to pass through openings in the rotating cylinder into the interior thereof from which the comminuted particles are pumped to the irrigation spraying location by the pump. The pump shaft has a drive shaft extension which extends through the center of the rotating cylinder to drive a planetary gear system arranged so that the rotating cylinder is driven at a speed much less than the pump speed.
It is the general object of this invention to provide alternate drive arrangements for a comminutor-pump assembly of the indicated type, which drive arrangements are simple and inexpensive. Briefly stated, the general object of the invention is achieved by simplifying the gear requirements of the prior comminutor-pump assembly by eliminating the planetary gear system and substituting a simpler arrangement therefor.
One alternate drive arrangement comprises a gearbox constructed and arranged to be driven directly by a tractor power take-off and comprising a gear arrangement for stepping up the drive shaft for the pump and stepping down the drive shaft for the comminutor cylinder
Another alternate arrangement involves the use of a piping bypass arrangement wherein the comminutor cylinder is driven directly from the tractor power take-off shaft and another shaft extending from the cylinder is arranged to drive the pump through a speed increaser gearbox. The piping arrangement involves the provision of a discharge pipe from a chamber in flow communication with the inside of the comminution cylinder and piped around to the inlet of the pump.
Another alternate arrangement is similar to that shown in said prior application except that it is provided with a hydraulic system consisting of a hydraulic pump that is driven by the pump impeller shaft and supplies hydraulic fluid to a hydraulic motor constructed and arranged to drive the comminutor cylinder at a reduced speed.
Another alternate involves the use of an electric motor which has one drive shaft connected to the impeller of the pump for driving the same and another drive shaft arranged through couplings or the like to drive a hydraulic pump. The hydraulic pump is arranged to drive a hydraulic motor which drives the comminutor cylinder at a reduced speed.
Another alternate involves the use of an electric motor arranged to drive the impeller shaft of the pump at a high speed and a second electric motor arranged to drive the comminutor cylinder at a low speed.
Another alternate involves the provision of a propeller on the impeller shaft for the pump at the inlet thereto to suppress the release of gas or cavitation bubbles at this low pressure region.
The details of the various alternate drive arrangements will be described more fully hereafter.